//
// Created by ASUS on 2024/10/19/星期六.
//
#include <bits/stdc++.h>
using namespace std;

int dx[4]={-1,0,0,1},dy[4]={0,-1,1,0};

void func(){
	vector<vector<int>> grid;
	int m=grid.size(),n=grid[0].size();
	auto dfs=[&](auto&&dfs,int x,int y)->int{

		for(int i=0;i<4;i++){
			int nx=x+dx[i],ny=y+dy[i];
			if(nx>=0&&nx<m&&ny>=0&&ny<n&&grid[nx][ny]!=0){
				grid[nx][ny]=0;
				dfs(dfs,nx,ny);
			}
		}

		return 0;
	};

	dfs(dfs,0,0);
}